The last Roman legions leave England to contain the invasions of the Germans on the mainland; they promise to return but they do not return and the British Isles will go through a dark period in which they will remain subject to invasions by the Angles, the Saxons, the Vikings, the Norwegians, the Danes, etc.; with the Romans the ability to build masonry fortresses disappears from the British Isles and Christianity almost disappears.
